WO2021085820A1 - Decrosslinked polyolefin resin for cable filler and resin composition comprising same - Google Patents

Abstract

The present invention relates to a decrosslinked polyolefin resin for a cable filler, and a resin composition comprising same. Specifically, the present invention relates to a decrosslinked polyolefin resin, and a resin composition comprising same, the decrosslinked polyolefin resin satisfying the mechanical properties such as tensile strength and elongation percentage to the high standard required in order to be applied as a material for a cable filler, and also having excellent processability, shrinkage percentage, flame retardancy, and the like, and reducing the production costs of a cable filler.

Description

De-crosslinked polyolefin resin for interposing cables and resin composition containing the same

The present invention relates to a de-crosslinked polyolefin resin for intervening cables and a resin composition comprising the same. Specifically, the present invention satisfies mechanical properties such as a high level of tensile strength and elongation required to be applied as a material for intervening cables, and at the same time has excellent processability, shrinkage, and flame retardancy, and can reduce the manufacturing cost of the cable intervening. It relates to a de-crosslinked polyolefin resin and a resin composition comprising the same.

In a submarine cable including a plurality of power line units (hereinafter referred to as'cores') and optical units for transmitting power by having a conductor, the plurality of cores are substantially symmetrical to the center of the submarine cable. It is arranged as an enemy, and a protective layer is provided along the periphery thereof.

However, in the above configuration, since a plurality of the core portions are provided, it may be difficult to maintain the roundness of the submarine cable. The same external force may act to cause damage to the core part provided inside the submarine cable. Accordingly, it is necessary to maintain the roundness of the submarine cable and to protect the inner core portion when the submarine cable is installed or when an external force such as an external pressure is applied.

1 schematically shows a cross-sectional structure of a cable including an interlayer for the cable.

As shown in Fig. 1, a cable including an interposition for a cable is one or more communication lines 100, one or more power lines 200, and is disposed between them to implement roundness and protect them from external shocks. It may include an intervening 300, a binder 400 that entirely surrounds them, a metal sheath 410, an outer jacket 420, and the like.

However, the conventional interlayer 300 for cables has insufficient mechanical properties such as tensile strength and elongation, and the intervening is pressed due to the tension of the steel wire during the sheathing process of the cable, so that the roundness of the cable is not secured. There is a problem that the cable is damaged locally due to the uneven distribution of the applied load on the cable, and if a material with excellent tensile strength and elongation is applied, the workability, shrinkage rate, flame retardancy, etc. are insufficient, or the manufacturing cost of the cable interlayer increases. .

Therefore, there is a desperate need for a material that satisfies mechanical properties such as high-level tensile strength and elongation required for application as a cable interlayer material, has excellent workability, shrinkage, and flame retardancy, and can reduce the manufacturing cost of the cable interlayer. The situation is being demanded.

The present invention satisfies mechanical properties such as high level of tensile strength and elongation required to be applied as a material for cable interlayers, while excellent workability, shrinkage, and flame retardancy, and de-crosslinking that can reduce the manufacturing cost of cable interlayers. It is an object of the present invention to provide a polyolefin resin and a resin composition comprising the same.

In order to solve the above problems, the present invention,

A polyolefin resin decrosslinked for recycling after crosslinking to be applied as a material for cable intervening, its weight average molecular weight (Mw) is 50,000 or more, polydispersity (PDI) is 5 to 15, and the gel fraction is 5% by weight or less. , Based on the total weight of the decrosslinked polyolefin resin, the content of the resin having a molecular weight of 10,000 or less is 5% by weight or more and less than 25% by weight, and the content of the resin having a molecular weight of 500,000 or more is 2 to 10% by weight, decrosslinked polyolefin Provide resin.

Here, the content of the resin having a molecular weight of 10,000 or less is greater than the content of the resin having a molecular weight of 500,000 or more, and the content of the resin having a molecular weight of 10,000 or less is 34% or less of the content of the resin having a molecular weight of more than 10,000 and less than 500,000. It provides a crosslinked polyolefin resin.

In addition, it provides a de-crosslinked polyolefin resin, characterized in that the tensile strength is 1.3 kg / mm 2 or more and the elongation rate is 380% or more.

And, it provides a de-crosslinked polyolefin resin, characterized in that the weight average molecular weight (Mw) is 50,000 to 250,000.

Furthermore, the polyolefin resin provides a de-crosslinked polyolefin resin, characterized in that it contains a polyethylene resin.

On the other hand, it provides a crosslinked polyolefin resin, characterized in that the crosslinked polyolefin resin is prepared by decrosslinking with a supercritical fluid as a reaction solvent under a reaction temperature of 250 to 350 ℃ and a reaction pressure of 5 to 30 MPa.

In addition, the crosslinking is a silane crosslinking, and based on the total weight of the resin, it provides a de-crosslinked polyolefin resin, characterized in that the content of silicon (Si) is 0.05 to 2% by weight.

Meanwhile, it provides a polyolefin resin composition comprising the de-crosslinked polyolefin resin and the non-crosslinked polyolefin resin in a weight ratio of 5:95 to 50:50.

Here, it provides a polyolefin resin composition, characterized in that the weight average molecular weight (Mw) is 50,000 or more, and polydispersity (PDI) is 5 or more.

In addition, a compatibilizer, a flame retardant, an antioxidant and a lubricant are additionally included, and based on 100 parts by weight of a mixture of a resin and a compatibilizer, the content of the flame retardant is 50 to 200 parts by weight, providing a polyolefin resin composition. .

Here, the flame retardant is made of aluminum hydroxide, magnesium hydroxide, calcium hydroxide, huntite (Mg ₃ Ca(CO ₃ ) ₄ ) and hydromagnesite (Mg ₅ (CO ₃ ) ₄ (OH) ₂ ). It provides a polyolefin resin composition comprising at least one inorganic flame retardant selected from the group.

On the other hand, it provides an intervening for a cable formed from the polyolefin resin composition.

The de-crosslinked polyolefin resin for cable intervening according to the present invention satisfies mechanical properties such as high level of tensile strength and elongation required to be applied as a material for cable intervening through a precisely controlled molecular weight distribution, and at the same time, processability, shrinkage, It exhibits excellent effects such as flame retardancy.

In addition, the de-crosslinked polyolefin resin for cable intervening according to the present invention is manufactured through recycling of de-crosslinking the cross-linked resin, thereby exhibiting an excellent effect of reducing the manufacturing cost of the cable intervening.

1 schematically shows a cross-sectional structure of a cable including an interlayer for the cable.

2 is a graph of tensile strength and elongation by content of a resin having a molecular weight of 10,000 or less in Examples.

Hereinafter, preferred embodiments of the present invention will be described in detail. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided so that the disclosed content may be thorough and complete, and the spirit of the present invention may be sufficiently transmitted to those skilled in the art.

The present invention relates to a polyolefin resin decrosslinked for recycling after crosslinking as a material for interposing cables, and a resin composition comprising the same. Here, the crosslinking includes crosslinking such as chemical crosslinking using a crosslinking agent such as an organic peroxide, silane crosslinking (or crosslinking) using a silane-based crosslinking agent, and irradiation crosslinking by electron beam irradiation.

The decrosslinked polyolefin resin for intervening cables according to the present invention may be prepared by decrosslinking the crosslinked polyolefin resin by a decrosslinking reaction for recycling of the crosslinked polyolefin resin.

The decrosslinking reaction may be carried out, for example, using a supercritical fluid as a reaction solvent under specific temperature and pressure conditions, and the decrosslinking polyolefin resin has a different molecular weight distribution depending on the temperature and pressure of the decrosslinking reaction, particularly a specific range. The content of the low molecular weight resin and the high molecular weight resin of a specific range, the gel fraction indicating the remaining crosslinked portion, etc. may be different, and accordingly, the mechanical properties, extrusion processability, shrinkage rate, etc. of the resin composition may be greatly different.

Specifically, the de-crosslinking polyolefin resin for intervening cables according to the present invention is manufactured by a de-crosslinking process to which process conditions such as a specific temperature and pressure are applied, so that the weight average molecular weight (Mw) is 50,000 or more, for example, 50,000 to 250,000, Premises that the polydispersity index (PDI) (Mw/Mn) is 5 or more, for example 5 to 15, and the gel fraction is 10% or less, for example, 0.5 to 5% by weight, precisely controlled molecular weight Distribution, specifically, based on the total weight of the de-crosslinked polyolefin resin, the resin having a molecular weight of 10,000 or less may be 5% by weight or more and less than 25% by weight, preferably 15 to 20% by weight.

Further, the content of the low molecular weight resin having a molecular weight of 10,000 or less is greater than that of the high molecular weight resin having a molecular weight of 500,000 or more, and the content of the low molecular weight resin having a molecular weight of 10,000 or less is 34% or less of the content of the resin having a molecular weight of more than 10,000 and less than 500,000, Preferably it may be 24.5% or less.

Here, when the content of the resin having a molecular weight of 10,000 or less is less than 5% by weight, the content of the high-molecular-weight resin with a molecular weight of more than 10,000 is relatively increased, and the viscosity and melting index of the de-crosslinked polyolefin resin are lowered, resulting in extrusion processability. On the other hand, when the content of the resin having a molecular weight of 10,000 or less is 25% by weight or more, the decrosslinking reaction proceeds at a high temperature exceeding 350°C when the crosslinked polyolefin resin for preparing the decrosslinked polyolefin resin is decrosslinked. In this case, as well as de-crosslinking, the tensile strength and elongation of the prepared de-crosslinked polyolefin resin may be greatly reduced by deterioration in which the main chain of the polymer is cut.

Accordingly, the de-crosslinked polyolefin resin according to the present invention can simultaneously secure a tensile strength of 1.25 kg/mm2 or more, preferably 1.3 kg/mm2 or more, and an elongation of 200% or more, preferably 380% or more.

In addition, the de-crosslinked polyolefin resin contains 2 to 10% by weight, preferably 2 to 3% by weight of a resin having a molecular weight of 500,000 or more based on the total weight thereof, so that it has excellent tensile strength compared to non-crosslinked polyolefin resins that have never been crosslinked. , Mechanical properties such as elongation, dimensional accuracy due to a low export rate, and excellent extrusion processability. In particular, the resin having the high molecular weight at a ^{specific shear rate, for example, about 100 s -1 or more during extrusion molding, is extruded in the extrusion direction.} It is orientated to, and rather reduces the overall viscosity of the de-crosslinked polyolefin resin to be lower than that of the non-crosslinked polyolefin resin, thereby remarkably improving the extrusion processability.

Here, when the polydispersity (PDI) is less than 5 or the content of the resin having a high molecular weight of 500,000 or more is less than 2% by weight or more than 10% by weight, the overall viscosity of the decrosslinked polyolefin resin at a specific shear rate or higher is non-crosslinked polyolefin. It does not decrease below the viscosity of the resin, so the extrusion processability may be insufficient.

In addition, when the de-crosslinked polyolefin resin for cable intervening according to the present invention is decrosslinked after silane crosslinking, the silane residue remaining in the polymer chain of the decrosslinked polyolefin resin may further improve the flame retardancy of the decrosslinked polyolefin resin. Here, the chemical structure of the silane moiety may be -SiOCH ₃ , -SiOH, -Si-O-Si-, or the like.

In addition, the content of silicon (Si) in the silane residue may be 0.05 to 2% by weight based on the total weight of the resin. When the content of silicon (Si) is less than 0.05% by weight, the degree of improvement in flame retardancy may be very insignificant, whereas when it exceeds 2% by weight, the viscosity of the de-crosslinked polyolefin resin increases. Processability and filler loading may be deteriorated, and on the contrary, flame retardancy may be deteriorated.

In the de-crosslinked polyolefin resin for intervening cables according to the present invention, the polyolefin resin may include an olefin-based homopolymer such as polyethylene and polypropylene, or an olefin-based random or block copolymer made of a polymer of two or more olefin monomers. , Preferably polyethylene. The polyethylene may be ultra low density polyethylene (ULDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), or a combination thereof.

The de-crosslinked polyolefin resin for interposing cables according to the present invention is a crosslinked polyolefin resin, for example, a reaction solvent under a reaction temperature of 250 to 350°C and a reaction pressure of 5 to 30 MPa, which is lower than the conventional decrosslinking reaction temperature inside a uniaxial compressor. It can be produced continuously by decrosslinking by means of a critical fluid.

The supercritical fluid used as the reaction solvent refers to a material that reaches a critical state in which a gas and a liquid cannot be distinguished while a general liquid or gaseous material exceeds the limit of high temperature and high pressure, which is called a critical point. The density of molecules in a supercritical fluid is close to that of a liquid, but its viscosity is low, so it is close to a gas, and because of its rapid diffusion, its thermal conductivity is as high as water.

Therefore, when the supercritical fluid is used as a reaction solvent for the decrosslinking reaction, the concentration of the dissolved molecules, that is, the solvent around the solute, becomes extremely high, causing the decrosslinking reaction to occur. As the supercritical fluid, alcohols such as distilled water, methanol, ethanol, or a mixture thereof may be used.

The present invention relates to a polyolefin resin composition comprising the de-crosslinked polyolefin resin.

The polyolefin resin composition according to the present invention may include the de-crosslinked polyolefin resin and a non-crosslinked polyolefin resin that has not been crosslinked. Here, the weight ratio of the de-crosslinked polyolefin resin and the non-crosslinked polyolefin resin may be about 5:95 to 50:50.

The polyolefin resin composition according to the present invention may have a weight average molecular weight (Mw) of 50,000 or more, and a polydispersity (PDI) of 5 or more. Accordingly, the polyolefin resin composition can simultaneously implement excellent mechanical properties and processability.

In addition, the polyolefin resin composition according to the present invention may further include an ethylene vinyl acetate (EVA) resin to further improve filler loading properties of additives such as flame retardants. Here, the content of the ethylene vinyl acetate (EVA) resin may be 25 to 50 parts by weight based on 100 parts by weight of the mixture of the resin and the compatibilizer. When the content of the ethylene vinyl acetate (EVA) resin is less than 25 parts by weight, the level of improvement in filler loading property is insignificant, whereas when the content of the ethylene vinyl acetate (EVA) resin is more than 50 parts by weight, the mechanical and electrical properties of the polyolefin resin composition may be deteriorated.

The polyolefin resin composition according to the present invention may include additives such as flame retardants, antioxidants, and lubricants. The flame retardant is from the group consisting of aluminum hydroxide, magnesium hydroxide, calcium hydroxide, huntite (Mg ₃ Ca(CO ₃ ) ₄ ) and hydromagnesite (Mg ₅ (CO ₃ ) ₄ (OH) _{2 ).} It may contain one or more selected inorganic flame retardants.

Inorganic particles such as magnesium hydroxide (Mg(OH) ₂ ) used as the flame retardant are hydrophilic with high surface energy, whereas resins such as polyolefin are hydrophobic with low surface energy, so the inorganic particles are It has poor dispersibility and may adversely affect mechanical and electrical properties. Accordingly, in order to solve this problem, inorganic particles such as magnesium hydroxide may be surface-treated with vinylsilane, stearic acid, oleic acid, aminopolysiloxane, titanate-based coupling agent, or the like.

When the inorganic particles are surface-treated with vinylsilane or the like, a hydrolyzable group such as vinylsilane is attached by chemical bonding to the surface of the inorganic particles such as magnesium hydroxide by condensation reaction, and the silane group reacts with the resin, resulting in excellent dispersibility. Can be secured. In addition, the silane group may further improve the flame retardancy of the polyolefin resin composition.

The content of the flame retardant may be 50 to 200 parts by weight based on 100 parts by weight of the mixture of the resin and the compatibilizer. When the content of the flame retardant is less than 50 parts by weight, sufficient flame retardancy may not be realized, whereas when the content of the flame retardant is more than 200 parts by weight, processability such as extrusion moldability of the polyolefin resin composition may be greatly deteriorated. Meanwhile, other additives such as the antioxidant and lubricant may be included in an amount of 1 to 10 parts by weight based on 100 parts by weight of a mixture of the resin and a compatibilizer.

[Example]

De-crosslinked polyethylene resin compositions according to each of the Examples and Comparative Examples were prepared with the content, molecular weight distribution, and gel fraction of each molecular weight section as shown in Table 1 below, and tensile strength and elongation of the specimens prepared therefrom were measured, respectively. In particular, a graph showing tensile strength and elongation measured by content in a section having a molecular weight of 10,000 or less is as shown in FIG. 2.

		Example						Comparative example
		One	2	3	4	5	6	One	2	3	4	5	6
Content by molecular weight section (%)	10,000 or less	19	20	21	22	23	24	25	26	27	28	29	30
	10,000~500,000	79	76	74	75	75	74	72	73	72	71	70	69
	More than 500,000	4	4	5	3	2	2	3	One	One	One	One	One
10,000 or less/10,000~500,000(%)		24	26	28	29	31	32	35	36	38	39	41	43
Gel fraction (% by weight)		2.5	2.5	2.3	2.2	2.1	2.1	1.6	1.5	1.2	1.1	0.9	0.4
Tensile strength (kgf/㎟)		1.334	1.411	1.423	1.419	1.368	1.312	1.2	1.19	1.098	1.088	0.85	0.73
Elongation (%)		390	405	430	465	455	395	180	230	255	225	150	125

As shown in Tables 1 and 2, the content of a resin having a molecular weight of 10,000 or less, assuming that the weight average molecular weight (Mw) is 50,000 or more, polydispersity (PDI) is 5 or more, and the gel fraction is 10% by weight or less. Examples 1 to 6, in which 5% by weight or more and less than 25% by weight, were excellent in tensile strength of 1.3 kg/mm 2 or more and elongation of 380% or more, whereas from Comparative Example 1, the content of resin having a molecular weight of 10,000 or less was 25% by weight. % Or more, the tensile strength decreased to less than 1.3 kg/mm 2, and in particular, it was confirmed that the elongation rate decreased rapidly.

Although the present specification has been described with reference to preferred embodiments of the present invention, those skilled in the art will variously modify and change the present invention within the scope not departing from the spirit and scope of the present invention described in the claims described below. You will be able to do it. Therefore, if the modified implementation basically includes the elements of the claims of the present invention, it should be seen that all are included in the technical scope of the present invention.

Claims (12)

1. As a crosslinked polyolefin resin for recycling after crosslinking to be applied as a material for interposing cables,

   The weight average molecular weight (Mw) is 50,000 or more,

   Polydispersity (PDI) is 5 to 15,

   The gel fraction is 5% by weight or less,

   Based on the total weight of the decrosslinked polyolefin resin, the content of the resin having a molecular weight of 10,000 or less is 5% by weight or more and less than 25% by weight, and the content of the resin having a molecular weight of 500,000 or more is 2 to 10% by weight, a decrosslinked polyolefin resin .
2. The method of claim 1,

   The content of the resin having a molecular weight of 10,000 or less is greater than that of the resin having a molecular weight of 500,000 or more, and the content of the resin having a molecular weight of 10,000 or less is 34% or less of the content of the resin having a molecular weight of more than 10,000 and less than 500,000. Suzy.
3. The method according to claim 1 or 2,

   Tensile strength is 1.3 kg / mm 2 or more, characterized in that the elongation is 380% or more, de-crosslinked polyolefin resin.
4. The method according to claim 1 or 2,

   The de-crosslinked polyolefin resin, characterized in that the weight average molecular weight (Mw) is 50,000 to 250,000.
5. The method according to claim 1 or 2,

   The polyolefin resin is characterized in that it comprises a polyethylene resin, de-crosslinked polyolefin resin.
6. The method according to claim 1 or 2,

   A crosslinked polyolefin resin, characterized in that produced by decrosslinking with a supercritical fluid as a reaction solvent under a reaction temperature of 250 to 350°C and a reaction pressure of 5 to 30 MPa.
7. The method according to claim 1 or 2,

   The crosslinking is a silane crosslinking,

   Based on the total weight of the resin, characterized in that the content of silicon (Si) is 0.05 to 2% by weight, de-crosslinked polyolefin resin.
8. A polyolefin resin composition comprising the de-crosslinked polyolefin resin of claim 1 or 2 and the non-crosslinked polyolefin resin of claim 1 or 2 in a weight ratio of 5:95 to 50:50.
9. The method of claim 8,

   A polyolefin resin composition, characterized in that the weight average molecular weight (Mw) is 50,000 or more, and the polydispersity (PDI) is 5 or more.
10. The method of claim 8,

    Further comprising a compatibilizer, flame retardant, antioxidant and lubricant,

    Based on 100 parts by weight of a mixture of a resin and a compatibilizer, the content of the flame retardant is 50 to 200 parts by weight.
11. The method of claim 10,

    The flame retardant is from the group consisting of aluminum hydroxide, magnesium hydroxide, calcium hydroxide, huntite (Mg ₃ Ca(CO ₃ ) ₄ ) and hydromagnesite (Mg ₅ (CO ₃ ) ₄ (OH) _{2 ).} A polyolefin resin composition comprising at least one selected inorganic flame retardant.
12. An intervening for a cable formed from the polyolefin resin composition of claim 8.

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